JP2564362B2 - Magnetic recording / reproducing device - Google Patents

Description

The present invention relates to a magnetic recording / reproducing apparatus, and more particularly to a rotary head type digital audio tape recorder (hereinafter referred to as DAT).

[Conventional technology]

In DAT of the rotary head system, in order to perform high-speed random music selection (cueing of music) at a speed of several tens to several hundred times the normal playback speed, a signal indicating the start of the music recorded in the track, It is necessary to accurately read the control signal recorded at the same recording density as the music PCM signal such as a signal for displaying the time and the music number information signal when the tape is running at high speed.

By the way, when the tape is run at a high speed at a speed different from that at the time of normal recording / playback, the scanning locus of the head crosses a plurality of signal tracks recorded on the tape, and if the cylinder rotation speed is constant, the relative head-tape The speed changes.

On the other hand, in the DAT, a data punching (data strobe) circuit is used as a circuit for reproducing a digital signal from a signal reproduced from the head, but normally, the input transmission rate of this circuit has a margin for the speed deviation and jitter of the tape running system ±. It is around 10%, the relative speed with the head changes due to the high speed running of the tape, and the transmission rate of the input signal is ± 10
If it deviates from the range of around%, data reproduction is impossible, that is, random access cannot be performed.

Therefore, in DAT, the cylinder rotation speed cannot be made the same as that during normal recording / reproduction when the tape is running at high speed, and the relative speed between the head and the tape is always constant, or the tape is within the allowable jitter of the data strobe circuit. It is essential to perform follow-up control according to the traveling speed of the vehicle. As a device that controls the relative speed of the tape and head by changing the rotation speed of the cylinder according to the running speed of the tape. For example, there is one described in JP-A-61-214164. These devices control the cylinder rotation speed so that the reproduction clock frequency obtained as a frequency synchronized with the reproduction signal in the data strobe circuit becomes a predetermined fixed frequency.

In the above high-speed access control, the tape speed, that is, the rotation of the reel motor that drives the reel base, cannot be rapidly increased at the same time when the access is started. This is because if the tape speed is suddenly increased, the cylinder tracking servo described above will be out of lock due to the delay in tracking the rotation speed due to the inertia of the cylinder. The number of rotations of the reel motor must be slowly raised.

[Problems to be Solved by the Invention]

The prior art described above does not consider the starting speed of high-speed tape running. When the tape speed, that is, the rotation of the reel motor that drives the reel base, is suddenly started, the follow-up control of the cylinder rotation speed is lost, and the head There was a problem that the relative speed of the tape was shifted and the data could not be reproduced.

The object of the present invention is to keep the following control of the cylinder rotation speed at the start of high-speed running of the tape, and to detect this after the tape reaches a predetermined speed to keep the original tape speed constant. In addition to the smooth switching to the control by the running control means, the tape high speed running control is performed even when the tape speed cannot reach the predetermined speed even if the tape winding load exceeds the control range of the circuit. It is an object of the present invention to provide a reel motor starting device capable of starting a control operation by means.

[Means for solving the problem]

For the above-mentioned purpose, first, in order to prevent the cylinder rotation speed following servo from being disengaged at the start of high-speed tape running, the rotation speed of the reel motor should be gradually raised. This can be achieved by setting the voltage applied to the reel motor in the open state to a gentle ramp voltage. However, if a gentle lamp voltage is applied from the start of starting the reel motor, there is a dead zone in the motor, and therefore a loss time occurs before the reel motor starts to rotate, which is not preferable.
For this reason, a ramp voltage having a steep gradient is applied until the reel motor starts rotating to reduce the loss time, and after the reel motor starts rotating, the ramp voltage is switched to a gentle ramp voltage.

Further, in order to smoothly switch the control of the reel motor from the gradual start-up by the ramp voltage to the high speed running control means with a constant tape speed, the tape speed is monitored and the value reaches the control center of the high speed running control means. Is detected and switching control is performed.

Further, regarding the point that the tape speed does not reach the predetermined speed even when the ramp voltage reaches the maximum control value due to the large tape winding load, for example, the value of the ramp voltage is monitored to detect that it is abnormal. Then, the control of the reel motor is forcibly switched to the control by the high speed traveling control means.

[Action]

The rotation detecting means of the reel stand outputs a rotation signal in synchronization with the rotation of the reel stand. When the reel motor starting means first generates a ramp voltage having a steep gradient at the same time as the search start command to start the reel motor, and then the reel stand moves to detect the edge of the rotation signal from the rotation detecting means of the reel stand. It operates so as to output a gentle ramp voltage, and when the rotation speed of the reel motor is further increased by the ramp voltage and the tape running speed reaches a predetermined speed, it receives a control signal from the tape running speed detecting means and receives the control signal at that time. It operates to hold the lamp voltage at the previous value. The tape running speed detecting means monitors the running speed of the tape, and when the speed reaches a control target value of the tape high speed running control means, it detects it and outputs a control signal, and the discriminating means is a reel motor starting means. The value of the lamp voltage output from is determined, and when the value reaches the maximum value of the control range, the control unit outputs the predetermined control signal.

Further, the control means receives the control signals of the tape traveling speed detecting means and the discriminating means, and outputs a signal for controlling the switching means so that the control loop by the tape high speed traveling control means is closed when either one of the control signals is inputted. To work. Further, the adding means works to add the control signals of the tape high speed running control means via the reel motor starting means and the switching means, and the output signal thereof is supplied to the reel motor.

With this configuration, after the reel base, that is, the tape starts to move, the tape speed gradually rises in response to the rotation of the reel motor due to the gentle ramp voltage from the reel motor starting means, so that the servo that follows the cylinder rotational speed is unlocked. It does not cause

Further, when the tape running speed reaches the control target value of the high speed running control means by the ramp voltage of the reel motor starting means, the control means is operated by the control signal from the tape running speed detecting means and the control loop by the tape high speed running control means. Is closed, the control operation is performed to keep the tape speed constant thereafter, and even if the tape winding speed is large and the ramp voltage reaches the maximum control value, the tape running speed is the control target value of the high speed running control means. If you can't reach
This time, the control signal from the discriminating means operates so that the control loop of the tape high speed running control means is closed, so that the tape can be prevented from running at low speed endlessly and the control operation can be rapidly shifted to the constant speed. .

〔Example〕

Hereinafter, specific examples of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, 1 is a cylinder, 2a and 2b are magnetic heads, 3 is a magnetic tape, 4 and 5 are tape reels, reel reels for feeding and sending, 6 are reel motors, 7 are connected to reel motors, and reel motors rotate. Gears for driving the reel bases 4 and 5, 8 is reel motor starting means, 9 is discriminating means, 10 is tape traveling speed detecting means, 11 is controlling means, 12 is switching means, 13 is adding means, and 14 is High-speed tape running control means, 15 is a cylinder rotation speed control means for variably controlling the cylinder rotation speed so that the relative speed to the head becomes constant according to the tape speed, 16 is a cylinder motor for driving the cylinder 1, and 17 is a system. 3 shows a system control microprocessor that controls the control of the.

In the embodiment shown in FIG. 1, as described above, at the start of the search, the switching means 12 is opened to open the servo loop, and the reel motor starting means 8 outputs a ramp voltage having a steep slope to start the reel motor. After detecting the movement of the reel base, the ramp voltage gradient is switched to a gentle one to gradually increase the tape running speed, and the tape speed reaches the control target value of the tape high speed running control means 14. This is detected by the tape running speed detecting means 10, the control means 11 is operated by the control signal to close the switching means 12, and thereafter the tape is run at a predetermined speed by servo control by the tape high speed running control means 14. In addition, even when the tape speed cannot reach the control target value of the high speed running control means 14 even though the ramp voltage has reached the maximum control value, the ramp voltage is controlled at the maximum. It was determined by determination means 9 that reaches a value, but to rapidly transition to the control operation by the high-speed running control means 14 forcibly closes the switching means 12 in the control signal.

A specific example of the cylinder rotation speed control means 15 is constituted by, for example, the device described in Japanese Patent Laid-Open No. 61-110359. Also,
The tape high speed running control means 14 is also, for example, the well-known reel stand 4
And a servo loop in which the period sum of the FG signals synchronized with the respective rotation speeds of 5 is constant. These circuit configurations and control operations are well known, and since they are not directly related to the essence of the present invention, details thereof will be omitted.

The operation of the reel motor starting control, which is the subject matter of the present invention, will be described below while presenting a concrete configuration example of each part.

FIG. 2 shows the configuration and operation waveform of the reel base rotation detecting means included in the reel motor starting means 8. In the figure (a), 18 is attached integrally with the reel stand 4, and the surface thereof is, for example, an aluminum foil that has been treated with black at regular intervals on the circumference as shown in the figure, and 19 is a photodetector, 20
Is an edge detection circuit. The light emitted from the light emitting element of the photodetector 19 is irradiated to the aluminum foil 18, and the reflected light is received by the light receiving element of the photodetector 19, but the reflected light is the maximum in the part where the aluminum foil 18 is not black. Therefore, the output of the light receiving element is maximized, and the reflected light is minimized in the black portion so that the output of the light receiving element is also minimized. Therefore, the light receiving element output e ₀ of the photodetector 19 alternates in synchronization with the rotation of the aluminum foil 18 when the reel stand is rotating as shown in FIG. 7B, and when the reel stand is stopped. Is aluminum foil 18 and photo detector
Fixed voltage of "L" or "H" depending on the positional relationship of 19.
Therefore, when the reel base starts to rotate, the output e _{0 of the} photodetector 19 is changed from “H” to “L” as shown in (c), or as shown in (d) at time t ₀ when the reel base starts moving. Then, the signal is inverted from "L" to "H", and then changes alternately in synchronization with the rotation of the reel stand. The edge detection circuit 20 receives this signal and receives t _{0 in} (c) or (d) of FIG. The change point of the output e ₀ of the photodetector 19 is detected and the reel base rotation start detection signal e ₁ that changes from “L” to “H” is output at t ₀ . Note that the edge detection circuit is easily configured by a logic circuit or the like, and its specific example is omitted because it is well known.

FIG. 3 shows a concrete example of the ramp voltage generating circuit of the reel motor starting means 8 and its operation waveform. In the figure, 21 and 22 are constant current sources, 23 to 25 are switches, 26 is a capacitor, 27 is a sample hold circuit, 28 is a drive amplifier,
The same symbols as those in FIG. 1 indicate the same things.

The switch 24 is controlled by the control signal e ₁ of the reel base rotation detection means. When e ₁ is “L”, the contact is on the a side, and e ₁
When becomes "H", it operates to close to the b side. Switch 24
Is controlled by the control signal e ₂ of the system control microprocessor 17 which causes the switch to close when e ₂ is "H". Further, the sample hold circuit 27 operates to hold the voltage of the capacitor 26 to the previous value by the control signal e ₃ output from the tape speed detecting means 10 when the tape running speed reaches a predetermined speed after the reel motor is activated. To do. The switch 25 is also controlled by e ₃ , and when the reel motor is started, the contact moves to the c side and the control signal e ₃ is issued to operate the sample hold circuit 27, and at the same time the contact moves to the d side. Further, the DC constant current sources 21 and 22 are for constant current charging of the capacitor 26, and the respective current values I ₁ and I ₂ are set to I ₁ > I ₂ .

In such a configuration, when the search start key operation is performed as shown in the operation waveform of FIG. 7B, the system control microprocessor 17 outputs the control signal e ₂ shown in FIG. As a result, the switch 24 is closed and the reel motor is initially stopped. Therefore, the control output signal e ₁ of the tape traveling speed detecting means 10 is "L" as shown in (b), and the contact of the switch 23 is a side. close. Therefore, the constant current I ₁ flows from the constant current source 21 to the capacitor 26 via the switch 23 and the switch 24, and the capacitor starts to be charged. The contact of switch 25 is c until the tape running speed reaches the specified speed.
Since it is closed to the side, the output e ₄ of the lamp voltage generating circuit becomes as shown in (d) according to the charging of the capacitor. This voltage is in the form of a ramp that rises linearly with time by charging the capacitor 26 with a constant current. e ₄ is the first
As shown in the figure, the voltage is applied to the reel motor via the adding means 13, but when the voltage v _{0 at} time t ₀ exceeds the start dead zone of the reel motor, the reel motor starts to rotate and the reel base starts to move. At this time, the control output signal e ₁ of the reel base rotation detection means is inverted from "L" to "H" by the above-described operation, so that the contact of the switch 23 is switched from a side to b side to charge the capacitor 26. The current changes from I ₁ to I ₂ . Where I ₂
<Because of I ₁ , the terminal voltage of the capacitor 26, that is, e ₄ is
As shown in (d), for the gradient from the search start to t ₀ , t ₀
After that, the gradient becomes gentle with v ₀ as the initial value. t ₀
After that, the reel motor rotation speed, that is, the tape running speed gradually increases due to the gentle ramp voltage e ₄ , but at time t ₁ when the tape running speed reaches a predetermined speed, the tape running shown in (c) is performed. The sample and hold circuit 27 operates by the control signal e ₃ from the speed detecting means 10 to hold the voltage of the capacitor 26 at the previous value, and at the same time, the switch 25
Since the contact point of is switched from the c side to the d side, e ₄ is held at the terminal voltage V ₁ of the capacitor 26 at time t _{1 as shown} in (d).

After t ₁ , the switching means 12 shown in FIG. 1 is closed, and the tape high speed running control means is based on the hold value V ₁ of e _4.
A predetermined tape running speed servo operation by 14 is performed.

FIG. 4 shows the configuration and operation of the discrimination means 9. In the figure, 29 is a voltage comparator and 30 is a reference voltage. Reference voltage 30, than the control maximum value of the lamp voltage e ₄ output from the reel motor starting means 8 is set to V _S is slightly smaller value, the lamp voltage e ₄ is V _S as shown in FIG.
The voltage comparison control signal e ₅ is output in the state of exceeding.

FIG. 5 shows the structure and operation of the tape running speed detecting means 10. In the figure, 31 and 32 are reel base rotation speed detecting means on the tape winding side and the feeding side, 33 and 34 are f-V converters, 35 is an adder, 36 is a voltage comparator, and 37 is a reference voltage. The same reference numerals as those in FIG. 1 indicate the same things. Here, the reel base rotation number detecting means 31 and 32 are constituted by, for example, the same photodetecting device as shown in FIG. 2, and are synchronized with the rotation of the reel base 4 on the tape winding side and the reel base 5 on the sending side, respectively. Output a rotation signal. The fV converters 33 and 34 independently output a voltage proportional to the frequency of the reel base rotation signal output from the reel base rotation number detection means 31 and 32, respectively, and the fV conversion characteristics thereof. Are set to the same.

By the way, when the tape is run at a high speed at an arbitrary constant speed, there is a property that the sum of the rotation frequencies of the reel bases on the sending side and the winding side becomes substantially constant over the entire tape area according to the running speed. Qualitatively, when the tape running speed is constant, the tape diameter on the take-up side gradually increases as the tape is taken up, and the number of rotations of the reel stand on the take-up side decreases accordingly. This is because the tape delivery side is due to the fact that the reel base rotation speed increases as the tape diameter gradually decreases, which is well known. Therefore, it is possible to know the running speed of the reels regardless of the position of the tape by detecting the sum of the rotation speeds of both reel stands. By controlling the rotation of the reel stand, the tape can be run at a predetermined constant speed. The example in FIG.
Utilizing this property, the outputs of the fV converters 33 and 34 are added by the adder 35 to generate e _M , which is compared with the reference voltage 37 to detect the tape running speed. It was done. The value of the reference voltage 37 is set to V _Q which is slightly smaller than e _M which matches the predetermined tape speed by the tape high speed corresponding control means 14 in FIG. Therefore, when the tape running speed increases, e _M increases, and when the tape speed reaches the control target value of the tape high speed running control means 14 and e _M > V _Q as shown in FIG.
36 operates to output a control signal of "H".

Further, the control means 11 is constituted by an OR logic gate, and when one of the control signal e _{3 of the} tape running speed detection means 10 and the control signal e ₅ of the discrimination means 9 is in the "H" state. The control means outputs an "H" control output, and the switching means 12 is constituted by an open / close type switch and operates so that its contact is closed when the control means 11 outputs a "H" control output.

The configuration and operation of each unit have been described above. The overall control operation in such a configuration will be described below.

FIG. 6 shows the operation. When the search command e ₂ is issued from the system control microprocessor 17 as shown in (a), the reel motor starting means 8 (b)
The ramp voltage with a steep slope is output, and the reel motor is started. When the reel base starts to move at time t ₀ , the ramp voltage e ₄ has a gentle slope according to the control signal e ₁ output from the reel base rotation detection means as shown in (c). After t _{0, the} reel motor gradually increases its rotation speed due to the gentle ramp voltage, and accordingly the tape running speed rises gently as indicated by the curve I shown by the solid line (e). And the time
At t ₁ , the tape running speed is the tape high speed running control means 14
When the control target value is reached, the tape traveling speed detecting means 10 outputs the control signal e ₃ as shown in (d), and the lamp voltage
When e ₄ is held at the previous value, the switch of the control means 12 is closed. As a result, after t ₁ , the tape is controlled to run at a predetermined high speed by the servo operation of the tape high speed running control means 14 centered on the hold value of the lamp voltage.

Furthermore, if the tape winding load is large,
The start of rotation of the reel base due to the ramp voltage having a steep slope is delayed, and the reel base moves at time t ₀ ′, at which point the slope of the ramp voltage is switched. After t ₀ ′, the rotation of the reel stand rises due to the gentle ramp voltage, but the tape speed is as shown by the broken line in (e) because the tape winding load is large.
It becomes gentler than the curve of I like the curve of II. And, there is no control signal e ₃ from the tape running speed detecting means 10 when the tape speed can not reach the control target value of the high-speed running control means 14 until the lamp voltage reaches V _M is the maximum value of the control At time t ₂ when the lamp voltage reaches V _M
Then, this time, the control signal e ₅ is outputted from the discrimination means 9 as shown in (e) and the switch of the switching means 12 is closed. As a result, after t ₂ , the tape speed is pulled to a predetermined speed by the servo operation of the tape high speed running control means 14 centered on the maximum control value V _M of the lamp voltage, and thereafter, the tape high speed running control means 14 keeps the speed constant. Control is made.

The embodiments of the present invention have been described above. The lamp voltage generating circuit of FIG. 3 is provided with two constant current sources and is switched to switch the gradient of the lamp voltage, but this is not particularly limited. For example, one constant current source is used. It is also possible to switch capacitors having different capacitance values. Further, although the circuit is also configured by analog, it is easy to configure it by a digital circuit. Further, although the edge detection circuit is provided independently in the example of FIG. 2, it is not particularly limited, and it is possible to give the system control microprocessor 17 this function, for example. Even if the tape running speed detecting means shown in the figure has a configuration capable of directly detecting the tape speed, similar control can be performed, and various modifications can be easily made within the scope of the present invention.

〔The invention's effect〕

As described above, according to the present invention, the reel motor is driven at a ramp voltage having a steep gradient at the start of the search, and after the reel motor starts to rotate, the ramp voltage is switched to one having a gentle gradient, and Not only when the tape speed reaches the predetermined speed due to the increase in the rotation of the motor, but also when the tape voltage does not reach the predetermined speed even though the ramp voltage has reached the maximum control value, this is detected to detect the original tape. Since the servo operation by high speed traveling control is closed,
Cylinder speed following servo can be prevented from being out of lock due to steep rise of tape running speed at the start of servo, and after tape speed reaches a predetermined speed due to ramp voltage, smooth and large tape winding load Even if the ramp voltage has reached the maximum control value and the tape speed cannot reach the specified speed, the tape is prevented from running at an infinitely low speed and the speed is kept constant. The tape running control can be performed.

[Brief description of drawings]

1 is a block diagram showing an embodiment according to the present invention, FIG. 2 is a diagram showing the configuration and operation of the reel rotation detecting means of the reel motor starting means of FIG. 1, and FIG. 3 is a reel motor starting of FIG. FIG. 4 is a circuit diagram showing the configuration and operation of the ramp voltage generating circuit of the means, FIG. 4 is a waveform diagram showing the configuration and operation of the discriminating means of FIG. 1, and FIG. 5 is a configuration of the tape running speed detecting means of FIG. FIG. 6 is a block diagram showing the operation, and FIG. 6 is a view showing the operation of the embodiment according to the present invention. 1 ... Cylinder, 3 ... Tape, 8 ... Reel motor starting means, 9 ... Discriminating means, 10 ... Tape running speed detecting means, 11 ... Control means, 12 ... Switching means, 13 ... Addition means .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keiji Noguchi Keiji Noguchi, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture Home Appliance Research Laboratory, Hitachi, Ltd. (72) Shozaburo Sakaguchi 25 Nishimachi, Kawagoe-shi, Saitama Prefecture 1 Pioneer Kawagoe Factory Co., Ltd. (72) Inventor Kenichiro Kawasaki 25-1 Nishimachi, Yamada, Kawagoe City, Saitama Pioneer Kawagoe Factory

Claims (1)

(57) [Claims] 1. A magnetic recording / reproducing apparatus for scanning a magnetic tape by a head mounted on a rotary cylinder to record a signal and reproducing the recorded signal, wherein a reel shaft on which the tape is mounted is driven. A high-speed running control means for running the magnetic tape at a speed higher than the normal recording / playback speed, and a cylinder rotation speed control means for controlling the cylinder rotation speed in relation to the speed of the magnetic tape. Reel motor starting means for generating a ramp voltage of an appropriate gradient together with a high speed running control start command of the magnetic tape, a judging means for judging the value of the ramp voltage of the reel motor starting means, and a running speed of the magnetic tape. A tape running speed detecting means for detecting and outputting a control signal when the tape running speed reaches a predetermined speed. Switching means for opening and closing the tape running speed control by means, control means for inputting output signals of the discriminating means and the tape running speed detecting means, and controlling the switching means according to the states of these signals, and the reel. The high speed running control means via the switching means, the control signal of the high speed running control means is added, and the adding means for driving the reel shaft by the added signal is provided. The tape speed is raised by the reel motor starting means with the switching means opened, and then the control signal of the tape running speed detecting means or the reel motor starting means output when the tape speed reaches a predetermined speed. When the lamp voltage reaches a predetermined value, the switching means is closed at the same time as the switching means is closed by a control signal outputted by detecting the lamp voltage. The generation of the ramp voltage of the driving means is stopped, and thereafter the reel shaft is driven by the addition signal of the control signal of the reel motor starting means by the adding means, that is, the final value of the ramp voltage and the control signal of the tape high speed running control means. A magnetic recording / reproducing apparatus characterized by performing high-speed running control of a tape.